Gaseous glow indicator tube formed on a substrate with a plurality of insulating layers

ABSTRACT

A gaseous glow indicator tube including a method of manufacturing and aging in which the elements of the indicator electrodes are arranged in a single plane by plating conducting segments on a base insulating plate which also carries a plurality of element energizing electrodes. The various elements of the indicator elements are individually connected to the energizing electrodes. Anode electrodes are mounted adjacent the indicator electrodes and are connected to anode energizing leads so as to selectively energize various indications. A method for aging the gaseous glow indicator is also disclosed.

United States Patent 1 Uemura et a1.

GASEOUS GLOW INDICATOR TUBE FORMED ON A SUBSTRATE WITH A PLURALITY 0FINSULATING LAYERS Inventors: Saburo Uemura, Yokohama;

Yuzuru Yanagisawa, Fujisawa, both of Japan Assignee: Sony Corporation,Tokyo, Japan Filed: Mar. 29, 1971 Appl. No.: 128,888

Related U.S. Application Data Division of Ser. No. 741,668, July 1,1968, Pat. No. 3,588,571.

Foreign Application Priority Data July 7, 1967 Japan 42/43782 US. Cl.29/25.]17, 313/109.5

Field of Search 313/1095; 29/625, 29/25.]7, 25.18, 2511, 25.13; 316/11,12

References Cited UNITED STATES PATENTS 6/1967 Bowerman 313/1095 [4 1July24,1973

3,378,920 4/1968 Cone 29/625 3,552,818 1/1971 Benda 3,573,532 4/1971B0ucher....

3,668,466 6/1972 Shimada 3,652,891 3/1972 Janning 313/1095 PrimaryExaminer-Charles W. Lanham Assistant Examiner-J. W. DavieAttorneyl-lill, Sherman, Meroni, Gross & Simpson [57] ABSTRACT A gaseousglow indicator tube including a method of manufacturing and aging inwhich the elements of the indicator electrodes are arranged in a singleplane by plating conducting segments on a base insulating plate whichalso carries a plurality of element energizing electrodes. The variouselements of the indicator elements are individually connected to theenergizing electrodes. Anode electrodes are mounted adjacent theindicator electrodes and are connected to anode energizing leads so asto selectively energize various indications. A method for aging thegaseous glow indicator is also disclosed.

12 Claims, 3 Drawing Figures PAIENIuJuL24|91s 3 M7. N 5

sum 1 OF 2 INVENTORS SABURO UEMUQA Yuzureu YANAMSAWA MKATTORNEY GASEOUSGLOW INDICATOR TUBE FORMED ON A SUBSTRATE WITH A PLURALITY OF INSULATINGLAYERS CROSS-REFERENCE TO RELATED APPLICATIONS This present applicationis a division of our pending application, Ser. No. 741,668, filed July1, I968 now U.S. Pat. No. 3,588,571.

BACKGROUND OF THE INVENTION 1. Field ofthe Invention The inventionrelates in general to gaseous glow indicator tubes and in particular toa novel gaseous glow indicator tube and method of manufacturing andaging such tube.

2. Description of the Prior Art Gaseous glow indicator tubes whichinclude a plurality of indicator cathode units mounted inside of atransparent envelope for providng displays of numerals, symbols, lettersor the like, have been commercially available. For example, theso-called Nixie Tube is a tube which'utilizes a transparent envelopethat contains an anode electrode and a plurality of cathode glowindicator electrodes aligned in a stack one above the other. Such tubesrequire substantial thickness because the electrode indicator units areplaced one above the other and a number of electrodes are used and arerelatively expensive to manufacture. Such tubes are difficult tomanufacture and are illegible unless the observer is directly in frontof the indicator tube. This is because the gaseous glow indicatorelectrodes are numerous and are mounted in different planes.

SUMMARY OF THE INVENTION The present invention relates to a gaseous glowindicator tube which has a plurality of indicator cathode units mountedinside of a transparent envelope with the indicator electrode unitsmounted in substantially the same plane. The indicator electrode unitsmay be formed with thin film techniques and each electrode is connectedto energizing leads by printed circuit or thin film conductors to obtainan efficient, inexpensive and compact unit. Mesh screen anode electrodesare attached over the indicator electrode units and are connected toenergizing electrodes by thin film or printed circuit techniques.

The printed circuit indicator assembly is placed into a transparentenvelope and sealed with a suitable ionizable gas such as neon with asmall amount of mercury so as to cause the cathodes to glow upon thesuitable energization of a cathode electrode and an anode electrode.

An aging apparatus and method is provided for rapidly aging a number ofcathode elements by applying energizing signals ona time sequence basiswhich provides a higher than normal operating potential so as to rapidlyage the indicators.

Other objects, features and advantages of the present invention will bereadily apparent from the following detailed description of certainpreferred embodiments thereof taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. lA through 1F illustrate themethod of fabrieating a glow indicator tube in accordance with thisinvention; 1

FIG. 2 illustrates a testing apparatus and method for testing a glowindicator tube according to this invention; and

FIG. 3 illustrates wave forms 1 through t which are used in theapparatus of FIG. 2 to test a gaseous glow indicator tube according tothis invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention relates to a glowindicator apparatus made with printed circuit techniques and results ina very thin unit. The number of weld and solder junctions aresubstantially reduced in the present structure and the symbols, lettersor numerals appear very clear because the electrode segments which arecaused to glow when energized are mounted in the same plane.

FIG. 1 illustrates a planar board 1 of insulating material upon whichthe individual indicator electrode units are to be attached by platingprocesses with suitable energizing leads. The particular unit beingillustrated in FIGS. ll comprises a IO-element indicator as illustratedin FIG. 1F. It is to be realized, of course, that any number of elementsmay be placed in the indicator device and they need not be placed in ahorizontal line but may be mounted at any position as, for example,vertically or in a matrix.

Each of the numerals 1 through 0 illustrated in FIG. 1F may beconstructed by using seven indicator elements with three of theindicator elements mounted horizontally and symmetrically on theindicator and with four of the indicator electrode elements mountedvertically on two opposite sides of the three elements.

By selectively energizing various of the indicator electrode elements,all of the numerals 1 through 0 may be produced. An additional period ordecimal element is also mounted to each of the numeral electrode elementgroups to provide a period or decimal where desired. FIG. IA illustratesa rectangular insulating base plate 1 which might be formed of aluminumoxide, for example, of a purity exceeding 92 percent. A plurality ofindicator units 3 through 3 are formed on the base plate I by suitablethin film techniques, as for example, printing and baking. For example,molybdenummanganese may be sintered in a hydrogen or ammonium gasatmosphere at about I,OO()C to produce a metalized plating. The sinteredmaterials are then plated with nickel and subjected to diffusion ofhydrogen gas at about 780C. The nickel plating prevents oxidation ofmolybdenum-manganese by the hydrogen gas diffusion and eliminates thenecessity of treatment in a non-oxidizing atmosphere in latermanufacturing processes.

Each of the indicator units 3 comprises three horizontal electrodesegments 2,, at the center of the plate I, 2., above segment 2, and 2below the segment 2,. On the left edge of these segments relative toFIG. 11B are formed the vertical segments 2 and 2 On the right edge ofthe horizontal segments are formed the vertical segments 2 and 2 Aperiod or decimal segment 2 is formed adjacent the electrode 2-,.Conductive segments 5 through 5 are connected to each of the indicatorelectrode segments 2 through 2H. Along the upper edge of the plate 1 areformed four energizing conductors 4 through 4,, and along the lower edgeare formed four more energizing electrodes 4 through 4 The strip 5 isconnected to the conductor 4, and the strip 5 is connected to theconductor 4 After the conductors 4, through 4,, and the electrodes andconnector strips 2, through 2,, and 5, through 5,, are formed on theboard, an insulating layer 6 is formed over the entire surface of thebase plate 1 except on the indicator electrode segments 2, through 2 andopenings 7, through 7, are left for each of the indicator units 3,through 3,,,. In addition, small windows 8, to 8 and 8,, to 8 are left.Also, small apertures 5, to 5 and 5,, to 5 are formed at the free endsof the strip conductors 5. The apertures 8, to 8 and 8 to 8 andapertures 5, to 5 and 5 to 5,, allow the electrode segments to beconnected to the leads 4, through 4 and 4 through 4 respectively. Theinsulating layer 6 may be formed by the silk-screen process in the samemanner as the electrode segments 2 and the leads 4 and strips 5 areformed. The insulating layer 6 may be formed, for example, of glass fritNo. 8190" manufactured by the Du Pont Corporation. The insulating layer6 may be formed by coating the glass frit on the base plate 1 two orthree times and then drying it in the air at 100C for to minutes. Theinsulating layer is further heated in an oxidizing atmosphere ofapproximately 300C for about 15 minutes to disperse a binder containedin the glass frit and thereafter is exposed to nitrogen gas at about850C for about 10 minutes in a quartz glass furnace to bake the glassfrit.

The connecting leads 9, to 9,, and 9 to 9,, are then formed over theinsulating layer 6 between the small apertures 5, and 8,, between 5 and8,, between 5 and 8 between 5 and 8 between 5, and 8,, and between 5,,and 8,, as shown in FIG. 1D. These connecting leads may be formed bysilk-screen printing techniques as, for example, by using a mixture ofsilver and palladium powder with glass frit. After the printing of theleads 9, the printed mixture is dried in the air at 100C to 225C forapproximately 10 to 15 minutes and is then heated in an oxidizingatmosphere of 300C or so for about 15 minutes to disperse a binder inthe mixture. It is then exposed to nitrogen gas for about 10 minutes ina quartz glass furnace maintained at 760 to effect baking of the printedmixture.

The second insulating layer 10 is formed over the insulating layer 6 tocover the connecting leads 9, but the windows 7, to 7, are again leftopen. The insulating layer 10 is formed in the same manner as the layer6 by fusing the glass frit over the layer 6, after which the unit isheld at 100C to 120C in the air for 10 to 15 minutes before placing itin an oxidizing atmosphere at about 360C for about 15 minutes todisperse the binder in the glass frit. Nitrogen gas is then passed overthe unit in a quartz glass furnace at about 850C for 10 minutes to bakethe insulating layer 10. The electrode segments 2, through 2,, may beplated with nickel before the formation of the insulating layer 10 orthey may be coated with a nickel layer after the formation of theinsulating layer 10. The nickel layer may be formed by electrolytic ornon-electrolytic plating, and it is desirable that the electrodesegments 2 be covered with a nickel layer thick enough to act ascathodes and that the nickel be of a purity in excess of 99.9 percent.

After the formation of the insulating layer 10, external leads I], to11,, are connected to the segment selecting leads 4, to 4,. The leads11, to 11,, are welded into one end of the base plate 1 at the positionscorresponding to the ends ofleads 4, to 4,, so that they make electricalcontact therewith.

Mesh screen anode electrodes 12, to 12, are attached to the base plate 1over each of the individual display units 3, through 3, and areconnected to external leads 14, to 14, which extend through the baseplate 1. Insulating partition walls or supports 13 are spaced on eitherside of each of the indicator units 3 and may be constructed, forexample, of mica or other similar insulating material. An insulatinglayer of glass frit or other similar material may be formed on the backof the base plate 1 in the manner as previously described.

The completed electrode assembly is placed into a transparent envelope,for example, a glass tube 15, as shown in FIG. 1F. The envelope 15 isfilled with an ionizable gas such as neon and a small quantity ofmercury and sealed. By applying a voltage potential to a particularexternal lead 14, to 14, of an anode electrode and to different externalleads 11, to 11,, which supply electrical potential to the segments 2,through 2,, various segments may be caused to glow.

To assure that the indicator electrodes 2, through 2,, produce uniformglow over their entire length, it is desirable to age or activate theelectrodes.

FIG. 2 illustrates apparatus to accomplish this. The device illustratedallows current to be sequentially applied between anode electrodes andeach of the indicator electrodes of each display unit to repeat thedischarge of current between them on a time-divisional basis.

In the case ofa gaseous glow indicator tube 16, which has, for example,15 display units, the electrode segment selecting leads are connectedtogether through resistors R, through R, with the other side of eachresistor connected to ground. The anode electrodes 12, m are connectedto a booster circuit 17 which receives an input from an oscillator 18. Acounter circuit 19 is connected between the oscillator 18 and thebooster circuit 17 to distribute the output of the oscillator to thevarious leads 14, through 14, to respectively energize the anode screens12, through 12, The counter circuit 19 distributes the output pulses ofthe oscillator 18 to the leads 14, to 14, so that each of the indicatorunits are sequentially turned on. For example, a wave-shape t,,illustrated in FIG. 3, is supplied to lead 14, to energize the anodeelectrode 12,, and waveshape t, which is slightly delayed from thewave-shape t, is supplied to the lead 14 etc. The pulses in FIG. 3might, for example, be microseconds in width and 1.5 milliseconds apart.Thus, it is seen that the drive is on a time divisional basis.

It is seen that this invention employs printing circuit techniques forthe manufacture of display discharge in dicators and substantiallyreduces the amount of welding required. For example, in the conventionalNixie Tube, 516 welding points are required for connecting theelectrodes of the indicator. In the present invention, as indicator tubeproduced according to this invention requires only 30 points of weldingor substantailly less than 10 percent as many as required in the NixieTube. The insulating layers 6 and 10 are formed by heating the baseplate 1 coated with the glass frit at 300C in an oxidizing atmosphere todisperse the binder contained in the glass frit and by heating the baseplate 1 at a temperature from 700C to 800C in an inert gas atmosphere tofuse the glass. This enables formation of the glass layers which formthe insulating layers without oxidizing the'metal of the electrodes orleads.

The base plate coated with glass frit may also be heated in a forminggas atmosphere to reduce lead contained in the glass to provide blackinsulating layers which enhances the contrast in color between thedischarge glow of the electrodes and the insulating layers and allowseasier interpretation of a number or symbol being displayed.

The aging apparatus illustrated in FIG. 2 allows units having 15 displayunits to be properly aged in about 15 minutes. Where each individualdisplay unit is aged in a sequential fashion, a minimum time of about 5minutes for each unit is required or a total of 75 minutes for 15 units.The unit of FIG. 2 allows 15 units to be aged in about 15 minutes for asaving of 60 minutes.

Although in the process described above, the connecting leads 9 to 9 and9 to 9 were formed after the insulating layer 6, is is to be realizedthat the selecting leads 4 to 4 and the various strip conductors may beformed in various sequences to obtain the same result. The insulatingbase plate 1 may be formed of glass, steatite or the like, if desired,rather than aluminum. When the base plate 1 is formed of ceramic, it ispossible that the base plate may be blackened by mixing an oxide withthe ceramic in the ratio of about 10 percent relative to the ceramic toprovide an indicator tube of good contrast. It is also to be realizedthat the electrodes may be formed on convex or concave portions of thebase plate which are aligned with the indicator units. This increasesthe distance between adjacent electrode segments and avoids undesirabledischarge between adjacent electrode segments. This also reduces thepossibility of short circuits between the electrodes due to sputteringcaused by discharge and thus lengthens the life of the indicator tube.

The electrode segments may be formed of usual conductive materials otherthan molybdenum-manganese. For example, silver-palladium film, palladiumfilm or gold-platinum film may be used. A silver-palladium film resultsin very stable connections.

When using silver-palladium film, it is coated on the base plate byprinting techniques, dried in the air at a temperature-of 100C to 120Cfor 10 to minutes and is then heated in an electric furnace at about750C for 45minutes or so, thus hardeningthe film to provide theelectrode segments.

Although the present invention has been described in "connection with anindicator with individual units mounted in a row, it is to be realizedthat other arrangements of the indicator units may be made, such as incolumns or in a matrix. Also, it is to be realized that a plurality ofindicator units may be mounted in a single envelope.

Although minor modifications might be suggested by those versed in theart, it should be understood that we wish to embody within the scope ofthe patent warranted hereon all such modifications as reasonably andproperly come within the scope of our contribution to the art.

We claim as our invention:

1. The method of making a gaseous glow indicator tube comprising thesteps of:

forming a plurality of indicator electrode units each having a pluralityof segments with strip conductors on a planarv surface of an insulatingbase plate,

forming indicator electrode selecting leads on the base plate;depositing an insulating layer on the insulating base plate except overthe indicator electrode segments and the areas where the indicatorelectrode selecting leads and the strip conductors are to be connectedtogether, forming leads on the insulating layer to connect the indicatorelectrode selecting leads with the strip conductors such that theassociated segments of each indicator unit are connected to the sameindicator electrode selecting lead; and

depositing a second insulating layer on the base plate which leaves theindicator electrode segments uncoated. 2. A method of making a pluralityof indicator units for a gaseous glow indicator tube comprising thesteps of:

forming a plurality of indicator electrode units each having a pluralityof segments formed in thesame pattern, on a planar surface of aninsulating plate;

forming a first indicator electrode selecting lead on said insulatingplate on said planar surface along one longitudinal edge and which isconnected to similar first segments of each of said plurality ofindicator units;.

forming a second indicator electrode selecting lead on said insulatingplate on said planar surface along the other longitudinal edge and whichis connected to certain other similar second segments of each of saidplurality of indicator units;

depositing an insulating layer by silkscreen process on said insulatingplate so as to cover said first and second indicator electrode selectingleads, but not covering said segments; and

forming external leads on said insulating plate which are connected tosaid first and second indicator electrode selecting leads.

3. The method of claim 2 comprising forming a first plurality ofindicator electrode selecting leads along said one longitudinal edge ofsaid plurality of indicator electrode units and thereafter, through andover said insulating layer, means connecting said first plurality ofindicator electrode selecting leads to other associated similar ones ofsegments of the peredetermined pattern of said plurality of indicatorunits.

4. The method of claim 3 comprising mounting a plurality of anodeelectrodes adjacent each of said plurality of indicator units, andconnecting external anode leads to said anode electrodes.

5. The method of claim 4 comprising aging said plurality of indicatorelectrode units by repeatedly applying an energizing voltage betweensaid anode electrodes and said segments of said plurality of indicatorunits.

6. The method of claim 5 wherein said first and second indicatorelectrode selecting leads and said first and second plurality ofindicator electrode selecting leads are connected together through aplurality of impedances which have a common ground and said energizingvoltage has one side grounded.

7. The method of claim 5 wherein said energizing voltage is sequentiallyapplied to said anode electrodes of said plurality of indicator units.

8. The method of claim 7 wherein said energizing voltage is applied toeach of said plurality of indicator units in pulses between 50 and 200microseconds in width.

9. The method of claim 8 wherein said pulses are spaced between 1 and 2milliseconds apart.

10. The method of claim 3 comprising forming a second plurality ofindicator electrode selecting leads along said other longitudinal edgeof said plurality of 5 a plurality of segments arranged in the samepattern on a planar surface of an insulating plate;

forming a first indicator electrode selecting lead on said insulatingplate on said planar surface along one longitudinal edge and which isconnected to similar first segments of each of said plurality ofindicator units;

forming a second indicator electrode selecting lead on said insulatingplate on said planar surface along the other longitudinal edge and whichis connected to certain other similar second segments of each of saidplurality of indicator units; and

aging said plurality of indicator electrode units by repeatedly applyingvoltage to them through said first and second indicator selecting leadsin a timedivisional manner.

1. The method of making a gaseous glow indicator tube comprising thesteps of: forming a plurality of indicator electrode units each having aplurality of segments with strip conductors on a planar surface of aninsulating base plate, forming indicator electrode selecting leads onthe base plate; depositing an insulating layer on the insulating baseplate except over the indicator electrode segments and the areas wherethe indicator electrode selecting leads and the strip conductors are tobe connected together, forming leads on the insulating layer to connectthe indicator electrode selecting leads with the strip conductors suchthat the associated segments of each indicator unit are connected to thesame indicator electrode selecting lead; and depositing a secondinsulating layer on the base plate which leaves the indicator electrodesegments uncoated.
 2. A method of making a plurality of indicator unitsfor a gaseous glow indicator tube comprising the steps of: forming aplurality of indicator electrode units each having a plurality ofsegments formed in the same pattern, on a planar surface of aninsulating plate; forming a first indicator electrode selecting lead onsaid insulating plate on said planar surface along one longitudinal edgeand which is connected to similar first segments of each of saidplurality of indicator units; forming a second indicator electrodeselecting lead on said insulating plate on said planar surface along theother longitudinal edge and which is connected to certain other similarsecond segments of each of said plurality of indicator units; depositingan insulating layer by silkscreen process on said insulating plate so asto cover said first and second indicator electrode selecting leads, butnot covering said segments; and forming external leads on saidinsulating plate which are connected to said first and second indicatorelectrode selecting leads.
 3. The method of claim 2 comprising forming afirst plurality of indicator electrode selecting leads along said onelongitudinal edge of said plurality of indicator electrode units andthereafter, through and over said insulating layer, means connectingsaid first plurality of indicator electrode selecting leads to otherassociated similar ones of segments of the peredetermined pattern ofsaid plurality of indicator units.
 4. The method of claim 3 comprisingmounting a plurality of anode electrodes adjacent each of said pluralityof indicator units, and connecting external anode leads to said anodeelectrodes.
 5. The method of claim 4 comprising aging said plurality ofindicator electrode units by repeatedly applying an energizing voltagebetween said anode electrodes and said segments of said plurality ofindicator units.
 6. The method of claim 5 wherein said first and secondindicator electrode selecting leads and said first and second pluralityof indicator electrode selecting leads are connected together through aplurality of impedances which have a common ground and said energizingvoltage has one side grounded.
 7. The method of claim 5 wherein saidenergizing voltage is sequentially applied to said anode electrodes ofsaid plurality of indicator units.
 8. The method of claim 7 wherein saidenergizing voltage is applied to each of said plurality of indicatorunits in pulses between 50 and 200 microseconds in width.
 9. The methodof claim 8 wherein said pulses are spaced between 1 and 2 millisecondsapart.
 10. The method of claim 3 comprising forming a second pluralityof indicator electrode selecting leads along said other longitudinaledge of said plurality of said indicator units and thereafter, throughand over said insulating layer, means connecting said second pluralityof indicator electrode selecting leads to other associated similar onesof segments of the predetermined pattern of said plurality of indicatorunits.
 11. The method of claim 10 comprising forming a second insulatinglayer on said insulating plate so as to cover said first and secondplurality of indicator electrode selecting leads.
 12. A method of makinga plurality of indicator units for a gaseous glow indicator tubecomprising the steps of: forming a plurality of indicator electrodeunits having a plurality of segments arranged in the same pattern on aplanar surface of an insulating plate; forming a first indicatorelectrode selecting lead on said insulating plate on said planar surfacealong one longitudinal edge and which is connected to similar firstsegments of each of said plurality of indicator units; forming a secondindicator electrode selecting lead on said insulating plate on saidplanar surface along the other longitudinal edge and which is connectedto certain other similar second segments of each of said plurality ofindicator units; and aging said plurality of indicator electrode unitsby repeatedly applying voltage to them through said first and secondindicator selecting leads in a time-divisional manner.